Well, technically, it would be overstocked. 56 litres is about 15 US gal and the recommended stocking level - for a new tank is 1 inch of fish per US gal.
Cardinals can grow to 2 inches - so 8 of them is pushing it without the other fish.
Personally, though, I wouldn't have a problem with that stocking level once the tank is well established and if it was heavily planted - none of those fish are big waste producers. The only thing is - the galaxy rasboras are shoaling fish and would prefer to be in a larger group and they are now endangered in the wild - because of all the interest in them. Unless you're seriously thinking of breeding them I would choose another of the small rasboras, like the spotted (
Rasbora maculata) and have six of them and six cardinals.
Alternatively, forget the rasboras altogether and have some of the tiny corys for the bottom of the tank. Pygmy corys are lovely.
I'm not familiar with Bolivian red rams - but I'm presuming they are the same size as ordinary Bolivians. A German ram would be smaller.
If you're going to stock at a higher level than 1 inch per gallon - do it gradually and allow the tank to mature before you are fully stocked. Keep the tank well planted (it helps to keep ammonia levels down); test the water regularly when the fish are first added - and keep up with the water changes.
Different bog woods will affect the water pH to different extents - depends on the type, how it has been treated before you get it and how you treat it before it goes in the tank. The fish you are planning on getting like acidic water, though - so it shouldn't be a problem, unless your tap water is already very acidic.
Edit: You edited your post when I wasn't looking. What happened to the Bolivian ram?